I have a SQLite database with 6 tables. When I use an SQL command with 6 SELECT and UNION, if the result responds only to one table, everything is correct, but if the result involves more than one table, the text fields are truncated to 510 characters.

duh - hmm - the best answer would be to use another database - Firebird for example SQLite is a bit of a hard case since from a Zeos / Delphi point of view it doesn't have Varchar fields at all, only Memo fields... That said - Zeos tries to emulate Varchar fields by truncating SQLite Varchar fields.

Do you remember which SQL you used to create your tables? Could you provide a small example database and project? Did you try to use Zeos 7.2?